The invention relates to a process used to monitor the correct operation of a clothes drier, particularly the degree of drying of linen dried in said drier.
The invention applies to all types of clothes driers, wherein a load of previously washed linen is introduced wet and is taken out dry. It particularly relates to industrial and semi-industrial clothes driers, used particularly, but not exclusively, in laundries used to handle linen from hospitals.
In clothes driers, a load of linen is heated and turned for a generally adjustable period of time. A ventilation system is used to extract the water vapour released by the linen due to its heating from the drier. When the drying cycle set by the operator is complete, said operator opens the door of the drier and removes the load of linen that has just been dried.
Irrespective of the type of drier used, the dryness of the linen removed from the machine depends on the type of fabric, its moisture level when introduced into the machine, the heating temperature and processing time.
Generally, the heating temperature and the drier operating time are set manually by the operator, who makes these settings essentially as a function of the type of fabric and its moisture level when entering the drier. Therefore, the dryness of the linen removed from said drier totally depends on the operator""s seriousness, skills and experience.
When the linen processed is obtained from hospitals, for example, the washed linen may still contain bacteria. These bacteria grow even more rapidly while the residual moisture level of the dried linen remains high. Therefore, it is strongly recommended to be able to maintain said moisture level at zero or at a value as close to zero as possible.
The invention specifically relates to a process devised to monitor the linen drying efficiency in a clothes drier precisely and reliably, particularly to be able to guarantee that the residual moisture level of the linen dried in said drier is zero or sufficiently low to prevent rapid growth of the bacteria potentially present in the linen.
According to the invention, this result is obtained by means of a process to monitor the aseptic nature of the linen, prior to the opening of at least one door of a clothes drier, characterised in that it consists of determining the residual moisture level of the linen inside the drier, comparing said level to a maximum permissible threshold and emitting a door opening authorisation signal when the residual moisture level is below the maximum permissible threshold.
According to a preferred embodiment of the invention, the residual moisture level of the linen is determined continuously.
In addition, when the drier comprises a metal drum and at least one agitating trough insulated electrically from said drum, the residual moisture level of the linen is determined advantageously by measuring the electrical resistivity between the trough and the drum.
The maximum permissible threshold is, preferentially, adjustable.
Whether adjustable or not, said threshold is advantageously equal to not more than 2%.